The Court should and does operate in the best interests of the child. The problem in the past was that the male was the bread winner and couldn't look after the child from a hands-on availability aspect. So an unattractive mother would often gain custody. Things have changed in the workplace and now I believe the Court is more able to grant custody TRUELY in the child's best interest. The Bad Mom will not get custody.
The opinion and preference of the child should be paramount in any decision no matter what the age of the child might be.
